Excerpt from Ml Umar Palanpuri رحمة الله عليه’s speeches and notes.

One scholar confided in me that his family is not practicing. His wife and daughters don’t cover, and the sons’ business is impermissible. One day, he lost his temper, to which his family reacted unfavourably. So I advised him:

(1) First, win the hearts of your family so they become acquainted and gradually grow within the religion.

(2) Continuously assess whether one’s intention is pure or flawed. Is it solely for Allah or something else?

(3) How to speak?
“And tell My servants to say that which is best (hiya ahsanu)…” (17:53)

What does it mean ‘to say that which is best’? Speak with gentleness, etiquette and wisdom. Don’t adopt harshness without any reason.

Because in the same verse, Allah warns us:
“Satan certainly seeks to sow discord among them. Satan is indeed a sworn enemy to humankind.” (17:53)

Satan will use 'speech' to create conflicts among us. 

(4) What is the prophetic method for speaking ‘that which is best’ to increase faith? Talk about:
a. Allah’s greatness
“…when His verses are recited to them, it increases them in faith” (8:2)

b. Prophets
“…the stories of the messengers to reassure your heart” (11:120)

c. Hereafter
“…those who have firm faith in the Hereafter.” (2:4)

(5) Speak in a manner that makes them receptive. Avoid speaking in ways that lead to outright rejection.

Ali (rad) said, “Speak to people only according to their level of knowledge. Would you like Allah and His Messenger to be denied?”
(Bukhari 127)